1. Field of the Invention
The present invention relates to computer systems, and more specifically to a system and method for managing execution of computer program tasks.
2. Description of Related Art
Large computing systems have software task management facilities that accept batch processing software tasks, which are sometimes referred to as “jobs,” queue these jobs with or without prioritization relative to each other and then submit the jobs for execution as computing resources become available. These batch processing software tasks are often data processing intensive tasks that operate without human input or control once the structure of the software task is defined. Batch processing software tasks typically operate upon pre-computed or prepared data that is stored on or available to the computing system upon which the software tasks execute. Some software tasks operate on data that has been prepared by another software task, thereby requiring completion of the software task that prepares the data prior to the starting of the execution of the software task that will use that prepared data. Conventional software task management techniques include the ability to schedule such phasing of software task executions.
Some software tasks are computationally intensive and require a large amount of time to completely execute. An example of such a software task is a weather modeling program. Weather modeling tasks can take hours to execute. These weather modeling tasks are often required to be complete by a certain time in order to ensure that the weather model data (i.e., result) is available for a scheduled presentation. These weather modeling software tasks are also required to begin execution after a certain time when the input data is certain to be available. These two requirements can place tight limitations on the time when the weather modeling software task can begin execution. Such weather modeling software tasks are also often required to operate on computing systems that host software tasks from many users requiring various amounts of time to execute. These other software tasks may also be computationally intensive and require a considerable amount of time to execute. The accuracy with which a particular software task, such as a weather modeling processing task, is able to be initiated at a specified time is therefore limited when these software tasks share computing facilities with other software tasks that require a long time to execute.
Computing facilities that perform the processing for software tasks that require a long time to execute frequently consist of a number of computer systems that are interconnected. These interconnected computing system are able to be computer “clusters,” which are groups of computers that are interconnected via high speed communications between all computers of the cluster, or just a number of computers connected via electronic communications. The interconnected computers that form these computing facilities often have a central software task management system, that can be referred to as a “software task manager” for simplicity, in order to efficiently utilize the several interconnected computers. Conventional software task management systems are able to associate a priority with each software task that specifies the priority of that task relative to other software tasks that are to be executed. Software tasks are typically received by the software task manager and submitted for execution on the one or more computers that make up the interconnected computer system. When all of the computers are busy, conventional software task managers queue newly received software tasks for execution when the resources it requires become available.
The software task manager bases its selection of the next software task to submit for execution upon the priority that is assigned to the software tasks. Current software tasks managers are able to estimate the computational resource requirements for each software task and include this estimate in the selection of the next software task to be submitted for execution in an attempt to maintain an equal loading on all of the interconnected computers that are controlled by the software task manager.
Software task managers maintain prioritized queues of software tasks that have been received and are to be executed. Heavily utilized computing systems typically have a large number of software tasks waiting in one or more queues. Some software managers allow the status of a queued software task to be specified when the software task is submitted to the software task manager. A software task may be submitted with a status of “on hold,” whereby the software task is maintained within the queue but is not to be submitted to a computer for execution. These software managers also provide external interfaces that allow external processes to affect the status of software tasks that are in the queue maintained by the software task manager. One control of queued software tasks is to change the status of a queued software task from “on hold” to “idle.” An “idle” software task will be submitted to a computer for execution when computing resources become available. Many software managers restrict the ability to change the status of a queued task to specific or privileged users.
Despite the features available in current software task managers, there is needed an effective way to operate a computer system that processes software tasks so that a particular task is able to start at or very near a particular time.